The following abbreviations are herewith defined:
3Gthird generation3GPPthird generation partnership projectE-UTRANevolved UTRAN (also known as LTE or 3.9G)GSMglobal system for mobile communicationsHLRhome location registerLTElong term evolutionNCLneighbor cell listNode-Bbase stationQoSquality of serviceRATradio access technologyUEuser equipmentUTRANuniversal terrestrial radio access network
A proposed communication system known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE, LTE or as E-UTRA) is currently under discussion within the 3GPP. One specification of interest is 3GPP TS 36.300, V8.2.0 (2007-09), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8), which is incorporated by reference herein.
Significant changes are occurring in wireless networks such as digital cellular networks. First there was GSM, implementing one radio access technology (RAT) used in a network, which focused initially in voice service only. Later, GSM evolved to 2.5G (generation 2.5) providing low bit rate data connections. After this, 3G (third generation) networks, implementing another RAT (or RATs), were launched with the intention to satisfy users by offering medium data rates of few hundreds of kbps (kilobits per second). 3.5G (generation 3.5), implementing HSPA (high speed packet access) and yet another RAT, was quickly developed as an enhancement of 3G and the ability to provide the first true broadband data rates, e.g., in the order of 1 Mbps (megabits per second).
Currently, the standardization of Long Term Evolution (LTE), also known as 3.9G, is being considered, which implements yet other RATs. The LTE is capable of delivering wireless broadband access at high bit rates similar to or higher than the rates offered in fixed (e.g., wired) networks. LTE is built as a flexible network with different frequencies and corresponding bandwidths. This means that different kind of networks can be built inside LTE with different network capacities (e.g., in terms of bit rate, loading, etc). For example, LTE (10 MHz) or LTE (20 MHz), where MHZ is megahertz, can be offered according to the demands of high bit rate and capacity.
Although the new networks offer advantages, there are as yet unresolved problems based on the coexistence of the new and old RATs.
U.S. Patent Publication 2002/0087674 A1, U.S. Pat. No. 5,903,832, and U.S. Pat. No. 5,915,214 describe systems for network selection. However, the systems described do not consider the subscription level of the user and which RATs the user has access to in accordance to their subscription level.